Troy Deeney is set for his first appearance of the season when Watford host Bristol City in the Carabao Cup.
The Hornets club captain missed the opening-day draw against Liverpool as he recovered from a pre-season groin operation, and was an unused sub at Bournemouth on Saturday.
Younes Kaboul, Daryl Janmaat, Roberto Pereyra, Tommie Hoban, Craig Cathcart and Mauro Zarate are out injured.
Provisional squad: Gomes, Pantilimon, Britos, Kabasele, Prodl, Mariappa, Holebas, Femenia, Capoue, Hughes, Amrabat, Chalobah, Doucoure, Watson, Deeney, Success, Richarlison, Sinclair, Okaka, Gray.